Tire with bridged center grooves having improved wear performance without sacrificing hydroplaning performance

Abstract

A tread design for a tire is described herein that has excellent wear properties, hydroplaning resistance, and snow grip. The combination of features also makes it suitable for use in high torque high load conditions found in modern day light truck applications. The tread includes a plurality of tread features lateral sipes, lateral grooves, longitudinal sipes and longitudinal grooves, the longitudinal grooves arranged to form a plurality of ribs, each rib extending annularly around the tread and where adjacent ribs are separated by one of the longitudinal grooves, the plurality of ribs including a pair of shoulder ribs and a plurality of central ribs. At least two of the plurality of central ribs is continuous in the longitudinal direction and are separated by a bridged longitudinal groove. The center section of the tire tread having a higher CSR than the shoulder region of the tire.

What is claimed is: 
     
         1 . A light truck pneumatic tire comprising:
 a pair of annular bead areas spaced apart axially along a rotational axis of the tire;   a pair of sidewalls spaced apart axially along the rotational axis of the tire, each sidewall of the pair of sidewalls extending outwardly in a radial direction from one bead area of the pair of bead areas relative to the rotational axis;   a crown portion arranged widthwise between the pair of sidewalls and extending annularly around the tire;   the crown portion including a tread formed of elastomeric material arranged annularly around the crown portion and forming an outer, ground-engaging side upon which the tire is intended to roll upon, the tread having a thickness extending radially and a width extending axially, the tread forming a wearing portion the tire;   the crown portion further including one or more belt plies each forming a layer of elastomeric material reinforced with a plurality of elongate reinforcements spaced apart in an array, the one or more belt plies being arranged radially inward and below the tread;   the crown portion further including a pair of shoulders, each shoulder forming a portion of the crown arranged adjacent to each sidewall;   the crown portion further including a cap ply arranged radially outward from the one or more belt plies and between the tread and the one or more belt plies, the cap ply extending at least partially across a full width of at least one of the belt plies and being arranged at least partially within each shoulder, the cap ply forming a layer of elastomeric material reinforced with a plurality of elongate reinforcements spaced apart in an array;   the tread including a plurality of tread features extending a depth within the tread thickness which includes lateral sipes, lateral grooves, and longitudinal grooves, the longitudinal grooves arranged to form a plurality of ribs, each rib extending annularly around the tread and where adjacent ribs are separated by one of the longitudinal grooves, the plurality of ribs including a pair of shoulder ribs and a plurality of central ribs, each of the shoulder ribs arranged along one of opposing widthwise extents of the outer, ground-engaging side and within one of the shoulders and where the plurality of central ribs are arranged between the pair of shoulder ribs;   the plurality of tread features extending into the tread thickness substantially to a depth defining a skid depth of the tread, the skid depth being the thickness of the tread intended to be worn during the intended life of the tire tread;   wherein at least two of the plurality of central ribs is continuous in the longitudinal direction; and   wherein the at least two of the plurality of central ribs are separated from each other by at least one longitudinal groove, said longitudinal groove having at least one bridge.   
     
     
         2 . The tire of  claim 1  wherein the at least one bridge of the at least one bridged longitudinal groove possessing a longitudinal sipe. 
     
     
         3 . The tire of  claim 2  wherein the at least one bridged longitudinal groove has a plurality of bridged groove portions separated by a non-bridged groove portion. 
     
     
         4 . The tire of  claim 3  wherein the plurality of longitudinal ribs have a plurality of longitudinally spaced apart lateral sipes 
     
     
         5 . The tire of  claim 4  wherein the plurality of longitudinally spaced apart lateral sipes extend across the width of the plurality of longitudinal ribs. 
     
     
         6 . The tire of  claim 4 or claim 5  wherein the plurality of longitudinally spaced apart lateral sipes possess a pair of opposed surfaces within the sipe and the opposed surfaces make contact with each other when the tire is loaded. 
     
     
         7 . The tire of  claim 1 , wherein the at least one of the at least two plurality of continuous central ribs has at least one but less than five lateral grooves. 
     
     
         8 . The tire tread of  claim 1 , where each of the shoulder ribs have a width equal to 19% to 35% of the tread width. 
     
     
         9 . The tire tread of  claim 8 , where each of the shoulder ribs have a width equal to 19% to 25% of the tread width. 
     
     
         10 . The tire tread of  claim 1  further comprising a center section, the center section forming a portion of the crown extending between the pair of shoulders, the center section and shoulders, the center section having a center contact surface ratio, and the pair of shoulders having a first contact surface ratio and a second contact surface ratio, wherein the center contact surface ratio is greater than the first shoulder contact surface ratio and the center contact surface ratio is greater than the second contact surface ratio.